CHAPTER 3 BIOLOGICAL MOLECULES

Biological Molecules

By Onjila bouprasert Princess Sirindhorn’s College

CHEMICALS OF LIFE Photosynthesis converts light energy into the

chemical energy of sugars and other organic compounds. This process consists of a series of chemical reactions that require carbon dioxide (CO2) and water (H2O) and store chemical energy in the form of sugar. Light energy from light drives the reactions. Oxygen (O2) is a byproduct of photosynthesis and is released into the atmosphere. The following equation summarizes photosynthesis:

6 CO2 + 6 H2O → 6(CH2O) + 6 O2

sugar Photosynthesis transfers electrons from

water to energy-poor CO2 molecules, forming energy-rich sugar molecules.

When the plants are eaten, these carbon- containing biological molecules will become part of the animal which ate the plant.

Biological molecules into four main classes

Structure and Properties of Lipids-made of carbon (C ) , hydrogen ( H) , oxygen

(O) Atoms .-Lipids do not share a common structural

unit.-they are all insoluble in water.

Lipids

Groups of lipids

Fat and oil

wax

Groups of lipids

phospholipids

steroides

H2C

HC

O C

O

R1

O C

O

R2

H2C C

O

R3O

H2C

HC

OH

OH

H2C OH

HO C

O

R1

HO C

O

R2

C

O

R3HO

fatty acidsglycerol triglyceride

Triglycerides

Fats are formed when fatty acids become linked with glycerol.

Triglycerides

A triglyceride is a fat molecule which has three fatty acid chains

Attached to its glycerol backbone.

Weight for weight,triglycerides produce twice the amount of energy of carbohydrate. They are an important store of energy.

They are to store,being large,uncharge and insoluble in water.

They are stored in spaces around organs like the kidneys,and in the layers under the skin.

There are many different types of steroids. There are many different types of steroids. They are all lipids. Their functions vary. They are all lipids. Their functions vary. Some common steroids are:Some common steroids are:

SEX STEROIDSSEX STEROIDS ANABOLIC STERIODS ANABOLIC STERIODS

CHOLESTEROLCHOLESTEROL

TESTING FOR LIPIDS

•Grease spot test/Brown paper test

H2C

HC

O C

O

R1

O C

O

R2

H2C P

O

OHO

OH

Diacylglycerol phosphate

Phospholipids

Phospholipids make up the plasma membrane of cells. One end of the phospholipid molecule is water-soluble or

hydrophilic.The other end is water – insoluble or hydrophobic.

This allows the molecules to arrange of phospholipids.The water-insoluble end face ench other on the inside of the

membrane.While the water-soluble ends face the aqueous environment inside

and outside the cell.

HO

H

H

H

cholesterol

A B

C D1

2

3

45

6

7

8

910

11

1213

17

16

14 15

O

O

H

H

H

progesterone

Steroid

Common steroid is cholesterol. Like the phospholipid.

It contrains both water- soluble and water – insoluble end.

Steroid

Sturated fatsThe possible places on the cabon atoms

where Hydrogen could be attached are filled.The result is a straigh molecule.Easier to pack saturated fats exist as

solids as room temperature.

In which the carbon atoms can be made to accept additional hydrogen atom.

ศึ�กษาเพิ่�มเติ�ม http://www.nclark.net/ChemLife.html

http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13204

http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13304

http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13104